Now, FPL wants to put two new nuclear reactors at its Turkey Point plant on Biscayne Bay. The planning and licensing costs passed along to ratepayers have reached about $250 million, the lawsuit says.

Filed on behalf of one customer of each utility, it seeks to be certified as a class action – meaning anyone who pays bill to the utilities since 2008 could join the class and benefit, if the utilities lose the lawsuit.

In a statement to NBC6, FPL called the suit “egregious … frivolous and without merit. It’s exactly this type of politically motivated litigation that will ultimately cost our taxpayers and our customers, and put a heavy burden on state government.”

FPL notes the state has approved the process that allows it to charge ratepayers for reasonable and prudent costs associated the nuclear upgrades and expansions.

But letting the state oversee that process, the suit claims, is one reason it is unconstitutional. The suit claims only federal law can govern nuclear energy production.

A Duke Energy spokeswoman said the lawsuit should be dismissed. “Four other lawsuits challenging the constitutionality of Florida’s Nuclear Cost Recovery statute have been found to be without merit and rejected by Florida courts,” she said. The lawsuit, she added, was inaccurate in saying Duke Energy had abandoned its plans for two reactors in Levy County. “While we’ve made the decision to retire our Crystal River nuclear plant, we continue to pursue the license for the proposed Levy County nuclear project,” she said.

For its part, FPL says no one is being billed for work that has not been done.

As it seeks “required licenses and approvals needed to construct and operate” new reactors at Turkey Point, FPL said, it is “not pre-collecting money for construction. The funds being collected are associated with specific expenditures required by federal, state and local governments to complete the licensing process and are used only to reimburse FPL for money already spent. “

But the lawsuit, filed in the Southern District of Florida, claims that by passing along nuclear costs to ratepayers – who are on the hook even if the plants never get built – “Duke and FPL have been wrongfully enriched at the expense of their ratepayers arising from the improperly inflated electrical rate.”

The law firm behind the suit, Hagens Berman, of Seattle, has in the last six months filed class action complaints naming nearly 20 deep-pocketed defendants, including Mercedes-Benz, Apple, Nestle and Volkswagen.